Advanced Electrolyte Engineering for Low‐Temperature Sodium‐Ion Batteries

Given the abundance and low cost of sodium resources, sodium-ion batteries (SIBs) are considered promising alternatives to lithium-ion batteries (LIBs). Moreover, the unique electrochemical and chemical characteristics of SIBs indicate their substantial potential for low-temperature operation. However, low temperatures significantly reduce the intrinsic Na+ transport rate, sharply increase the Na+ de-solvation energy barrier at the battery-electrolyte interface, and lead to dynamic solid electrolyte interphase (SEI) reconstruction, resulting in a substantial increase in interfacial impedance. These issues ultimately lead to severe capacity degradation, diminished power performance, shortened cycle life, and even complete battery failure at low temperatures. To address these challenges, this review thoroughly analyzes the failure mechanisms of electrolytes at low temperatures and comprehensively summarizes current design and optimization strategies for low-temperature SIB electrolytes, including solvent engineering, concentration regulation, novel additives and sodium salts, and emerging electrolyte systems. Furthermore, it prospects the future development trends of organic electrolytes, aiming to provide insights for the advancement of novel low-temperature SIBs.